CORE SUMMARY/ABSTRACT The goal of the Sources, Transport, Exposure, and Effects of PFASs (STEEP) Center?s Community Engagement Core (CEC) is to facilitate a community-centered, participatory process to protect human health and inform public policy. The CEC will serve as the liaison between STEEP Center members and residents and stakeholders on Cape Cod, Massachusetts, in New England, and throughout the United States to: direct community engagement best practices to enhance a broad understanding of per- and polyfluoroalkyl substances (PFASs); promote and implement prevention and intervention strategies to reduce exposures to PFASs; protect human and ecological health; and inform public policy. The CEC aims to be responsive to the community?s needs by providing scientific expertise in response to community questions and concerns. The CEC will work with stakeholders, including residents, federal, state and local health and environmental agencies, public officials, non-governmental organizations, and ?sister? Superfund programs at the U.S. Environmental Protection Agency (EPA) and Agency for Toxic Substances and Disease Registry (ATSDR) to: facilitate bidirectional exchange of knowledge between stakeholders and researchers; enhance a broad understanding of PFASs; and promote and implement prevention and intervention strategies to reduce exposures to PFASs and protect human health. The CEC?s targeted communities are located on Cape Cod, Massachusetts, where multiple sources of PFASs (fire training areas, airports, military base, landfills, municipal wastewater, and septic systems) threaten the sole source aquifer that provides drinking water for 200,000 year-round and 500,000 summer residents. For instance, Joint Base Cape Cod (JBCC) is home to the Otis Air National Guard Base, one of 14 designated Superfund Sites for PFASs. PFASs from aqueous film forming foams (AFFFs) have migrated into groundwater near JBCC and near the Barnstable County Fire Training Academy (BCFTA); public drinking water wells near BCFTA are being treated to remove PFASs. Prior research by Silent Spring Institute demonstrated the presence of PFASs in private drinking water wells throughout Cape Cod. The CEC will work with each research project, the Research Translation Core (RTC), and Training Core (TC) to foster knowledge exchange between STEEP members and community members and stakeholders. The CEC will form a Cape Cod Advisory Committee (CCAC) and host an annual Spring Science Day on Cape Cod to provide opportunities for STEEP researchers and trainees to share new research findings and for stakeholders and community members to ask questions and inform research and engagement activities. The CEC will offer private well water testing for PFASs to Cape Cod residents, focused in areas near likely sources, and participants will receive context-rich, digital report-back of their own well results. Results from wells close to known sources will also inform Project 1?s fingerprinting of PFAS profiles in drinking water. The CEC will work with statewide and national NGOs and agencies to share STEEP Center research findings and promote effective strategies to reducing PFAS exposures from drinking water and other sources.